Means for preventing double exposures.



P. F. RICE. MEANS FOR PREVENTING DOUBLHEXPOSUBES.

APPLICATION FILED SEP T. 6, 1007.

Patented Nov. 10, 1908.

:1- -iliL%-t- L l i a open and close the shutter once,

UNITED sTATEsr TENT OFFICE.

PERCY r". RICE, F TUSTIN, CALIFORNIA, Asslouoa or ONE-THIRD TO EARL v.LEWIS AND ONE-SIXTH TO W. H. FAUST, B'O1 H- .0 I Los ANGELES,CALIFORNIA.

MEANS FOR PREVEIilTING DOUBLE EXPOSUBES.

Specifiqation of Letters Patent.

Patented Nov. 10, 1908.

Application filed ldpteniber 5.1907. Serial No- 391,443.

'ond time until after the film has been turned.

Another object is toprovide a device of this character which may beapplied to a camera of the folding type.

The accompanying drawings illustrate the" invention, and referriiigthereto :Figure 1 is a front elevation of a camera equipped with thisinvention. Fig. 2 is an enlarged detail view, in section, on line :c -wFig. 1, showing the parts in normal position. Fig. 3 is a view similarto Fig. 2, showing the parts in the position which they have im--mediately after the bulb has been pressed and prior. to the relaxationof the bulb.

Fig. 4 is a. view similar to Fig. 2, showing the osition of the partsimmediately after the ulb has been relaxed.

1 designates the case of the camera having the front folding table 2provided with a way 3 u on which head 7 is slida-bly mount-- ed, the ead7 being equipped with lens 8 and a shutter case 9, the shutter mechanismbeing operatedby a lever 10 andthe latter may be either manipulated byhand or by means of a pneumatic device comprising a cylinder 11 carryinga. plunger 12, air being forced into the cylinder 11, below the plunger12, by means of a rubber bulb 13 which communicates through a tube 14with the lower end of cylinder 11. By squeezing bulb 13 air forced intothe cylinder 11 to lift plunger 12 and operate shutter lrver'lO in thewell known manner.

In carrying out my invention I prefer to operate the same pneumatically,the part icular mode of o eration being to allow the plunger 12 to eraised by air ressureto ut -to prevent the plunger 12 from beingoperated a second time until the roll of film has been turned.

15 designates the film spool upon which which is connected by a flexibletube with 'a nipple 21 formed on the lower endof the roll of film iswound, the film spool being detachably connected with a ratchet -16, theratchet 16 being opera-ted by thumb piece 17. All these parts are wellknown in the art and do not need further description. Fixed to the case1 is a cylinder 18 shown in dotted lines in Fig. 1, and in section inFigs. 2, 3 and 4. The cylinder 18 has an end nipple 19 cylinder 11.Slidable Within the cylinder 18 is an intermediate cylinder 22 having aclosed outer end with a reduced diameter 23 forming an annular air 5 ace2.4, there being a stud 25 on its .end. he reduced end 23 is providedwith ports 26. WVithin the intermediate cylinder 22 is a plunger 27, theinner end of which is open. The plunger 27 is provided with lateralports 28 which are adapted to register with )orts 26 of the intermediatecylinder as will be explained. A. helical spring 30 is arranged betweenthe end of the plunger 27 and the-head of the intermediate cylinder 22.The stud 25 bears against a flat spring 32, the-latter being secured tothe side framework of the case 1.

The spring 32 base. lateral arm 33 formed with a detent 34 on its endwhich is adaptcd to be engaged with ratchet 16 before re-. ferred to. y

In the operation of the'device, just before operating the shutter tomake an exposure, the parts stand in the relative positions shown inFig. 2, with the ports 28 out of register with ports-26, the (plunger27being retracted, and the interme iate cylinder '22 retracted, and thedetent 34 of spring 33 being out of engagement with ratchet 16,

the spring 30 being compressed as the in termediate cylinder is heldback by the stronger sprin 32' By pressing bulb 13 air-- is forced intot e cylinder 'll'which lifts the plunger 12 and acts upon lever 10 toopen and close the shutter, the shutter 'being set for instantaneousexposures; at the same time the air is forced through the tube2O intocylinder 18 into the interior ofplunger 27 and as none of this air:escape it forces 'the intermediate cylinder 22 and plunger 27 to theright, both inoyin as one piece, and as the stud 25 presses I orward.spring 32 it causes detent 34 to engage with a tooth of the ratchet lGand the parts take the position shown in Fig. 3. The ports 26 and 28 arestill out, of register and air can- I spring 33 being retained by theratchet, and cylinder 22 is .inder 22 at this time not retracting as theIt should be-understood that through tube 20 into ports 28 and 26 intoannular space 2 and its retraction moves back cylinder 22 to nor notescape and solong' as this air pressure is maintained, inside of plunger27 the spring 30 is keptcompressed. When the hand of the operator allowsbulb 1.3 to relax the air pressure within plunger 27 reduces, whereuponthe spring 30 expands and moves the plunger 27 to the left, bringingports 28 into register with ports 26, the intermediate cyl spring 33exerts no pressure against it, the

held in contact against spring 32 by the reactive pressure of spring 30.the tension of spring 33 which is hooked to the ratchet is notsufiicient to turn the ratchet on account of the considerable relativepower required to turn the ratchet due to friction and fihn resistance.-The parts thus take the position shown in Fig. 4. It should beunderstood that the parts attain the position shown in Fig. 4practically instantaneously upon release of the pressure of bulb 13 asthe cylinder 22 and plunger 27 have a very slight movement, in facthaving even less movement than the lunger 12. a

It will now e observed that when the parts are in the position shown inFig. 4, if the bulb 13 be pressed in the attempt to expose the film asecond time that the air compressed by bulb 13 will not be effectiveagainst plunger 12 as this air will escape plunger 27 and through thenceout into the atmosphere. In such operation of bulb 13 the operator atonce. notices the nonresistance of bulb 13, and also notices that theshutter does not operate, which indicates to him that he has neglectedto turn a fresh film into place. Even though this fact is not noticed bythe operator it is impossible for him to operate the shutter by means ofbulb 13 and produce a double exposure, as every time the bulb 13 pressedthe air exhausts without operating lunger 12. The operator then turnsthe lilm spool 15 to bring another film into position which operatesratchet 16 clockwise, which is its only direction of movement, and thismovement of the ratchet allows spring to retract, and. the detent 34then disengages from ratchet 16 and the spring 33 in mal positioncompressing spring 30 and moving ports 26 out of register with ports 28,at which time the parts have again taken the position shown in Fig. 2,and the deviceis now in a position such that upon pressing bulb 13 theair will not be allowed to escape but will operate plunger .12 to worktie shutter. It will be noted that tube 20 permits of the focusingmovement of the lens so that the device operative in any position "ofthe lens. l

It should also be noted that this device will operate when the shutteris set for bulb T o eration instead of instantaneous alt 1011 h in'operating under the bulb the re axation of the bulb may take place withmore delay than under instantaneous.

It is obvious that when the shutter is adjusted to bulb that, inasmuchas the air pressure is not reduced until thebulb is relaxed by the hand,that the time interval between the positions shown in Figs. 3 and atwill be greater than when the shutter is set for instantaneous, thistime interval corresponding to the period that the bulb is held closedby the hand and the shutter open.

In operating when the shutter is set for a time exposure wherein twosuccessive pressures of the bulb are required to open the shutter andclose it the device also will operate, contrary to What would becasually apparent, for the reason that in a time exposure the secondpressure on the bulb need. be very slight compared to the first as iswell known because the first pressure must be strong to furnish thepower to set the shutter open, while the second pressure need onlyfurnish the small power required to release the shutter, the power forthe. opening and closing movements of the shutter having been providedby the first pressure. Thus in a time exposure, after the secondpressure, although the ports are in register and air can escape, itsescape is restricted sufficiently to cause the necessary slight pressureto build up to close the shutter, but as this slight pressure is verymuch less than that required for the opening movement of the shutter thedevice when Working under instantaneous or bulb prevents the secondexposure.

1 What I claim is 1. In a device for preventing double exposures, ashutter,means for operating the shutter, a film operating device, andpneumatic means intermediate the film operating device and the shutteroperating means for controlling the shutter, the said pneumatic meansbeing operable ,by the film operating device.

2. In a device for preventing double exposures, a shutter, pneumaticmeans for operating the shutter, a film operating device, andmeans'controlled by the film operating device for allowing or preventingair toescape from the pneumatic shutter operating means. 7

. 3. In a device for preventing double exposures, a shutter, pneumaticmeans for opcrating the shutter, v .a 'ilurality of telescopingcylinders having ports, a tube for conveying air from the shutteroperating means to said tubes, and

means enacting with the film spare-ting means for controll' the relativeposition ports, a helical spring between the plunger 0! said cylindersan their ports whereby and intermediate cylinder, a shutter, a cylair isallowed to escape or is prevented from inder 'and plunger for 0 atingthe shut- 15 escaping from said eylindm's. 1 ter, and a. tube extendingmthe latter cyl- 5 4. In a device for preventing double exinder to thefirst cylinder. w posures, a film operating: device including a Intestimony whereof, I have hereunto Set ratchet, a spring adapted toengage the my hand at Los Angeles, California, this retchet, astationary ey inder, an intermedi- 29th day of August 1907 ate cylinderslidable in the stationaz c'ylin- PERCY F. RICE. 1o and having exhaustports and earing In presence of-- said spring, a hollow plunger withinGEORGE T. Hncmr, intermediate cylinder having exhaust FRANK L. A-GRAHAM.

